1. Field of the Invention
The present invention relates to solid polyelectrolyte fuel cells, and, in particular, to the structure of a fuel cell electrode-membrane-frame assembly and a manufacturing method therefor.
2. Description of the Related Art
The solid polyelectrolyte fuel cell (hereinafter occasionally referred to as “PEFC”) is an apparatus for concurrently generating electric power and heat by electrochemically reacting a fuel gas that contains hydrogen with an oxidizer gas that contains oxygen such as air.
The most typical PEFC is constructed of a polyelectrolyte membrane with a gasket of a sealing member for sealing gas at the peripheral edge portion, an electrolyte membrane-electrode assembly (hereinafter referred to as “MEA”) constituted by joining an anode to one surface of the electrolyte membrane and joining a cathode to the other surface of the electrolyte membrane, and an anode side conductive separator plate and a cathode side conductive separator plate interposing the MEA therebetween. A gas feeding part for feeding the fuel gas and the oxidizer gas to the anode and the cathode, respectively, is formed at the peripheral edges of a center portion put in contact with the MEA inside the separator plates.
One of the important problems of PEFC is to improve the use efficiency of the fuel gas and the oxidizer gas. In concrete, MEA sometimes generates a gap between the inner edge of the gasket and the outer edge of an electrode layer (an electrode layer of the anode or cathode) for the reasons of restrictions and so forth on the processing steps. When such a gap exists, the fuel gas and the oxidizer gas leak to the gap in PEFC operation, and the leaking fuel gas and oxidizer gas are discharged to the outside while being scarcely exposed to the MEA. This consequently incurs reductions in the use efficiency of the fuel gas and the oxidizer gas, i.e., reductions in the efficiency (generating efficiency) of the PEFC. In order to solve the problems as described above, for example, Japanese unexamined patent publication No. JP 2001-155745 A proposes an MEA of a structure such that a gasket formed of a prescribed resin material for covering and sealing the outer edge of the electrode layer of the MEA is integrated with the MEA. Various other structures of the gasket integrated with the MEA or relevant techniques are proposed (refer to, for example, International Publication Pamphlet No. 2002/043172, JP 2006-310288 A, JP 2001-102072 A, JP 2006-252811 A, U.S. Patent Laid-Open No. 2004/0096730, U.S. Pat. Nos. 6,610,435, 6,840,969 and U.S. Patent Laid-Open No. 2004/0234831).